The offensive execution was there most of the night. The passes were crisp. The shots were in sweet spots. The results, however, were demoralizing.

The Celtics carried out their game plan well enough to beat the Milwaukee Bucks on Friday night at TD Garden. Rajon Rondo put his teammates in position countless times for the Celtics to add to their gamelong lead. But veterans Kevin Garnett and Jason Terry, who have carried their teams on dozens of nights with shots pounding the net and rhythm flowing, were as melodic as fingernails against a chalkboard.

The duo combined to miss a whopping 30 shots, their futility wiping out a stirring Celtics rally in the final minute of regulation that sent the game into overtime. The Bucks prevailed, 99-94, their third win this season over the Celtics, who again are stuck in the doldrums.

Paul Pierce’s 3-pointer with 2.5 seconds left in regulation capped a 7-point rally in the final 33.5 seconds, but the cold shooting carried into overtime, when the Celtics missed 8 of 11 shots and scored 4 points in the final 3:58.

Milwaukee relied on Monta Ellis and Larry Sanders, the guard-center tandem combined for 9 points in the extra frame, sending the Celtics into more confusion after what could have been a season-turning rally.

“I’m always jokingly — and it’s the truth — say it’s a make/miss league and tonight was evident of that,” an exasperated Doc Rivers said. “I mean, we had point-blank looks at the rim all through the game, and one of the best shooters in the NBA in JET [Jason Terry] and Kevin. So we got them great shots, just couldn’t make them, and I thought as the game went on, you know you press more and more to make them and we just couldn’t. So, it was one of those games.”

It’s been one of those games far too often this season for the Celtics, who continue to find ways to lose games that previous teams would have cinched. Five of their 13 losses are to Milwaukee and Philadelphia. The Bucks looked uninterested for most of the first three quarters, but poor shooting prevented the Celtics from pulling away.

“At halftime, I was concerned because I thought we should’ve been up 15 points and we were up 3,” Rivers said. “And it was the same thing. It was frustrating . . . we missed so many wide-open shots. We missed four layups. So you’re frustrated in the first half thinking ‘God, we should be up 20.’ And then the same thing happened in the second half except we missed more shots. So it was a frustrating game.”

Pierce followed his 40-point game Wednesday with 35-pointer on 13-for-23 shooting Friday night. But his teammates were a combined 23-for-71 shooting (32.3 percent) and 2 of 17 from the 3-point line. The Celtics held leads in the fourth quarter of their last two games with Milwaukee, but watched the Bucks chip away to victories.

“I haven’t watched the tape yet; I think I’m going to go back and watch the tape and say ‘Wow, I like what were we running,’ ” said Rivers. “We just couldn’t make a shot.”

The Celtics are a .500 team, but likely would have won a half-dozen more with better late-game execution. That is not lost on the players.

“That’s what we’ve been saying all year long,” Pierce said. “There are going to be nights shots won’t fall and the one thing we can control I think is the intensity on the defensive end. But we just — a little bit of consistency in that department — we play well for the most part and we look up there and we shoot 43 percent or whatnot, but it has to be throughout the whole game. More consistency. You know, we can’t give up 17-0 runs to Cleveland. We can’t give up 10-0 runs to Milwaukee. And then decide that’s when we want to play defense.”

The Celtics looked fried, trailing, 88-81, when Ellis sank a free throw with 42.2 seconds left. Pierce countered with two free throws and after two missed Brandon Jennings free throws, Jeff Green caught an alley-oop off a Rondo inbounds pass to make it 88-85 with 29 seconds left.

A trapping defense forced the Bucks into miscues and Jennings’s pass was picked off by Rondo as the clock ticked down. Terry missed the first 3-pointer, but Green chased the rebound and fed a trailing Pierce for the tying 3-pointer with 2.5 left.

A good portion of the crowd was headed out of the Garden, disappointed after seemingly another home loss. They soon were scurrying back down the aisles only to be crushed when the Celtics couldn’t seize the momentum in overtime.

“We had a chance to put them away in the first half and we just couldn’t get the stops,” said Terry, who is 6 of 32 in the past two losses to Milwaukee. “And then coming down the stretch, the ball just wasn’t going in. Give them a lot of credit but for us, that’s a game you have to win. We’ll learn from it. I know for me, this is a tough night, a tough one to swallow.”